Download presentation
Presentation is loading. Please wait.
Published byJames Walton Modified over 8 years ago
1
The line of force or Field line direction is the path a small positive test charge would follow if free to move Electric field patterns An electric field pattern can be produced by using semolina grains sprinkled on oil between + & - high voltage metal conductors
2
The line of force or Field line direction is the path a small positive test charge would follow if free to move Electric field patterns + An electric field pattern can be produced by using semolina grains sprinkled on oil between + & - high voltage metal conductors
3
The line of force or Field line direction is the path a small positive test charge would follow if free to move Electric field patterns + + An electric field pattern can be produced by using semolina grains sprinkled on oil between + & - high voltage metal conductors 90 o
4
The line of force or Field line direction is the path a small positive test charge would follow if free to move Electric field patterns + + + An electric field pattern can be produced by using semolina grains sprinkled on oil between + & - high voltage metal conductors 90 o
6
Same charges repel, different charges attract Two types of charge + - + - - +
7
Same charges repel, different charges attract
8
How rubbing can produce static electricity At the start each material has no overall charge. Friction rubs electrons off the cloth onto the surface atoms of polythene. The polythene gains electrons and becomes negatively charged. The cloth loses electrons and becomes equally positively charged. However, acetate becomes positively charged
9
However, acetate becomes positively charged Insulators do not have any delocalised electrons, They are all firmly attached to individual atoms
10
What force keeps the electrons inside the atom?
15
‘positive charges’ Region of excess Delocalised electrons
16
Electrons in the metal object are repelled by the negatively charged rod Because ‘like charges repel” ‘positive charges’ Region of excess Delocalised electrons
17
Electrons in the metal object are repelled by the negatively charged rod Because ‘like charges repel” If the rod touches the conductor electrons flow off the rod and onto the conductor leaving both objects negatively charged ‘positive charges’ Region of excess Delocalised electrons
18
ELECTRICAL DISCHARGE A charged conductor can be discharged by connecting it to earth. + -
19
If the voltage is high enough the air molecules will ionise and a spark discharge occurs. - Ionisation is the ability to remove electrons from atoms leaving a trail of positive ions. Electrical potential energy or potential difference between the conductor and the ground
22
slowly and safely ( thick copper strip )
25
An experiment to show that current is a moving charge micro ammeter Carbon coated ball on nylon thread Van der Graff generator
26
An experiment to show that current is a moving charge Carbon coated ball on nylon thread + + _ _ _ _ The negative charges on the metal plate attract the ball
27
An experiment to show that current is a moving charge Carbon coated ball on nylon thread + + _ _ _ _ The negative charges on the metal plate attract the ball _ _ _ _ The ball receives negative charge and is repelled away carrying the charges across to the other plate
28
An experiment to show that current is a moving charge The faster the charges are carried across from one plate to the other the greater the current flows: Charge = Current X Time Q = I X T Coulombs Ampsseconds For AS PHYSICS we said:
29
Charge = Current X Time Q = I X T Coulombs Ampsseconds Example: Calculate the amount of charge flowing passed a point in a wire carrying a current of 5 Amps in 10 minutes.
30
Charge = Current X Time Q = I X T Coulombs Ampsseconds Example: Calculate the amount of charge flowing passed a point in a wire carrying a current of 5 Amps in 10 minutes. Q = I X T Q = 5 x 10 x 60 Q = 3000 Coulombs of charge
31
The faster the charges are carried across from one plate to the other the greater the current flows: Current flowing depends on : * Charge on the ball * Frequency of transfer So: I = Q f =Charge Q Time of one cycle
32
The faster the charges are carried across from one plate to the other the greater the current flows: Current flowing depends on : * Charge on the ball * Frequency of transfer So: I = Q f =Charge Q Time of one cycle QUESTIONQUESTION
33
The faster the charges are carried across from one plate to the other the greater the current flows: Current flowing depends on : * Charge on the ball * Frequency of transfer So: I = Q f =Charge Q Time of one cycle QUESTIONQUESTION
34
The faster the charges are carried across from one plate to the other the greater the current flows: Current flowing depends on : * Charge on the ball * Frequency of transfer So: I = Q f =Charge Q Time of one cycle QUESTIONQUESTION
35
The faster the charges are carried across from one plate to the other the greater the current flows: Current flowing depends on : * Charge on the ball * Frequency of transfer So: I = Q f =Charge Q Time of one cycle QUESTIONQUESTION
36
The faster the charges are carried across from one plate to the other the greater the current flows: Current flowing depends on : * Charge on the ball * Frequency of transfer So: I = Q f =Charge Q Time of one cycle QUESTIONQUESTION
37
Chips and Charge Electrons are attracted onto the chips pins via ‘earthed’ fingers If the ‘earth’ is removed the chips remain (oppositely )charged – by induction ! Tiny circuits get damaged
38
The line of force or Field line direction is the path a small positive test charge would follow if free to move Electric field patterns The electric field pattern can be produced by using semolina grains sprinkled on oil between + & - high voltage metal conductors + + + 90 o
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.